I Became the Little Demon in Leading Role's Family - Chapter 641 - 650 She’s Not Wrong, She is the Female Lead

Wang Bo was fed up with his job being a programmer, especially because of all of the nights he was working overtime without pay. His boss had given him a mysterious game to beta test in his free time, which had granted him possession of unclaimed territory in New Zealand with which to improve to his desires. After a certain event in his company, he ended up quitting his job. His lack of goals and curiosity eventually led him to buy a ticket to New Zealand, in order to see if the unclaimed territory given to him in the game was actually real. Watch, as he develops this beautiful, fertile stretch of land into prosperity, by building villages, farms, schools, hospitals and more.

- Description from Novelupdates

Ajax was an orphan who survives a massacre along with his friends but unfortunately gets separated from them.

Fortunately, after a turn of events, he successfully gains a system which helps him increase his cultivation, but doesn't know what it is called.

But he knows one thing for sure, this system is very powerful and helpful in taking his revenge.

“Whoever you are, I am gonna find you”, Ajax mumbled himself with a disgruntled expression.

In a world where Summoning of an elemental spirit is done through a dream when they are 15 years old, Ajax with the help of a system and his summoned spirits sets out on a journey to seek revenge against the mastermind behind the massacre.

A continuation from where High School DxD Volume 25 left off.

Ji Huan’s parents both died in a traffic accident.
Unexpectedly, his older sister also meets the same fate.
Yet everything starts when he says “goodbye” for the last time.

Hunting monsters? Genetic comparison?
Ji Huan flees with his older sister’s posthumous child to his hometown, Bade Town.
The three Grandpa, grandson, and nephew all live interdependent days.
However, inside the swaddling clothes is not a human baby,
But a monster…

Black egg body, white ring eyes, red mouth.
A child, ah! Doesn’t he have two eyes and a mouth! Resembling an egg, he is Ji Huan’s cute nephew!

Vermilion tiled wall, white lotus pond, convalescent courtyard.
This entirely neatly handsome and elegant young man: Ah Jin.
However, he told Ji Huan about the secrets of the monsters and discreetly taught him.
Bade Town is also slowly being covered in monsters…

Or, the record of a small countryside monster’s growth.

- Description from Novelupdates